Back now with Day to Day. As we just heard, one of the films out this weekend is called "Nick and Norah's Infinite Playlist." It's based on an award-winning novel of the same name. Day to Day's Alex Cohen recently spoke with the book's authors, David Levithan and Rachel Cohn. And she brings us this story.

ALEX COHEN: David and Rachel like to make up stories including ones about how they met. David jokes that they found each other on a deserted island. Rachel says they met through a Jewish dating website.

Mr. DAVID LEVITHAN (Author, "Nick and Norah's Infinite Playlist"): I was just a sinner. You walked in right from the door. Opened for Elijah and then I was like oh, wait. It's Rachel.

COHEN: In real life, the two came to know each other a few years ago through the world of YA or young adult literature. David is an editor with Scholastic Press and Rachel had written several YA novels. The two shared a lot in common including a love of music and movies.

(Soundbite of movie "Thin Man")

Unidentified Woman: How many drinks have you had?

Unidentified Man #1: This will make six martinis.

Unidentified Woman: All right, will you bring me five more martinis? You all line them right up here.

Unidentified Man #2: Yes, ma'am.

COHEN: Rachel is an especially big fan of the 1930's "Thin Man" series. She says she was inspired by the constant banter between Nick and Norah Charles, the funny and often inebriated couple who solve crimes.

Ms. COHN: I remember one day, I was walking around the reservoir at Central Park and I was just thinking about the "Thin Man" movies and I was thinking oh, it would really be fun to write a book about two characters named Nick and Norah and just kind of make them straight edge kids from New Jersey.

COHEN: But Rachel was worried about writing the Nick character. She had tried writing from a guy's perspective before and felt she hadn't quite gotten it right. So she called David.

Mr. LEVITHAN: I believe her exact words were, I need a guy writer. I said OK, sure.

Ms. COHN: Yeah. It was only later that I told him he was the only guy writer I knew at the time.

Mr. LEVITHAN: Yeah. I'm still flattered, well no I'm actually not - but the key was that we decided we would alternate chapters. And Rachel said 'so I have these two characters, Nick and Norah. It'll all take place in the night. Now, you go write the first chapter.'

COHEN: And so he did. In the first chapter, David created Nick, a high school senior from Hoboken. Nick's the heterosexual bass player in a band with two gay teens who play a style of music called queer core.

Mr. LEVITHAN: And that's really all you actually need to know about Nick because it shows that he is obviously very comfortable with his friends, very comfortable with his life. And the bassist is always the very quiet, very brooding one who really sets the undertone for everything else in the band.

Ms. COHN: Yeah. And that was a nice thing to do for Norah because that girl does not fall in love with that guy.

COHEN: David emailed that first chapter to Rachel and then she wrote a chapter about Nick's soon-to-be love interest Norah, the daughter of a record company exec.

Ms. COHN: She comes across as very aggressive, but she is kind of a tender little tiger under all of that. Her dad says about her, he never know what kind of Alanis moment she's going to have if she's going to be the tender "Thank You" Alanis or the raging "You Ought to Know" Alanis.

(Soundbite of song "You Ought to Know")

Ms. ALANIS MORISSETTE: (Singing) You, you, you ought to know.

COHEN: Alanis would be Alanis Morissette, one of dozens of musical references peppered throughout the novel. In fact, it was music that inspired the book's title.

Ms. COHN: We kind of always knew it would be Nick and Norah something. And then in David's last chapter, there was this one section where Nick refers to songs going from chord to chord, from song to song.

Unidentified Man: I always think of each night as a song or each moment as a song. But now I'm seeing we don't live in a single song. We moved from song to song, from lyric to lyric, from chord to chord. There is no ending here. It's an infinite playlist.

COHEN: Writer, David Levithan.

Mr. LEVITHAN: We were going back and forth a little bit about titles and Rachel said 'how about "Nick and Norah's Infinite Playlist"?' I was like 'wow! That sounds good. Where did you get that from?' Because I totally had no memory of having written the passage.

COHEN: There's a good reason why David likely forgot what he wrote. It all happened pretty fast with Rachel writing Norah from Berkeley, California and exchanging chapters with David, taking on Nick in New York City.

Mr. LEVITHAN: It was rare that it would take more than a day or two before the other person responded. We didn't talk about the book at all...

Ms. COHN: Yeah. That helped a lot.

Mr. LEVITHAN: While we were writing it. We didn't know what was going to happen next until we got the next chapter.

Ms. COHN: We just sort of did it and had fun. It was almost like exchanging a very, very long email with, you know, a really great friend.

COHEN: Rachel says there were few changes from the original version to published book. And most of those had to do with the music - the nods to Green Day, Debbie Harry, The Ramones, The Spice Girls and what David describes as this black lipstick oldie from The Cure.

(Soundbite of song "Pictures of You")

THE CURE: (Singing) I've been looking so long at these pictures of you that I almost believe that they're real.

Ms. COHN: One of the things that we spent the most time on in the editing of the book was going through every single musical reference in the book to make sure that any band name stood the test of time. And that was on two levels. Either one, because they were that good or number two, because they were that bad.

(Soundbite of song "I Wanna Sex You Up")

COLOR ME BADD: (Singing) Girl, you know I'm hooked on you.

Mr. LEVITHAN: Rachel kept trying to put in Color Me Badd references, and I was just like it's not going to fly.

(Soundbite of song "I Wanna Sex You Up")

COLOR ME BADD: (Singing) I wanna sex you up.

COHEN: OK. So the duo might not have always agreed on musical taste, but they did see eye to eye on most other things including sex. Though the book was written for teenagers, Rachel Cohn and David Levithan had no qualms about writing very frankly about sex. There's a scene in a burlesque club where strippers dressed like nuns. There are girls kissing girls and Nick and Norah shared a very intimate scene by an ice machine in a Marriott Hotel.

Mr. LEVITHAN: Originally, there were going to be wearing promise rings never do anything. I know - I think when you are high school seniors and you are meeting somebody, sex is certainly part of the equation.

COHEN: But the book is more than just a kind of thing that gets furtively passed around by school kids who've earmarked the dirty parts. It's also very much an old fashion love story.

(Soundbite of music)

Mr. LEVITHAN: Another reason the Beatles made it so big…

COHEN: There's a scene in the book where Nick, fearful he's blown hic chances with Norah, is consoled by his gay band mate, Dev. The two were sitting on the curve and Dev gently takes Nick's hand.

(Soundbite of song "I Wanna Hold Your Hand")

BEATLES: (Singing) I wanna hold your hand.

Mr. LEVITHAN: "I Wanna Hold Your Hand," first single, perhaps the most brilliant song ever written because they nailed it. That's what everyone wants.

COHEN: Writer, David Levithan.

Mr. LEVITHAN: That's the essence of what people are attracted to. That's what the essence of a love song is. It's not about sex. It's not about humpedy hump. That was what the passage was about. It was about when we play love songs, and when we write books that are love stories. Really, it's about that belonging of the holding of the hand much more so than about anything else.

COHEN: Right now, writers David Levithan and Rachel Cohn are working on solo projects. I asked them if they plan on writing another book together anytime soon.

Mr. LEVITHAN: You never know.

Ms. COHN: Never say never.

Mr. LEVITHAN: It is an infinite playlist.

COHEN: Alex Cohen, NPR News.

BRAND: And to see a picture of David and Rachel, the duo behind "Nick and Norah" and to hear one of the songs on the soundtrack to the movie, you can go to our website, npr.org.

(Soundbite of music)

CHADWICK: Day to Day is a production of NPR News with contributions from Slate.com. I'm Alex Chadwick.

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